After nearly two full years without an MMA fight, McGregor returned to the Octagon on Oct. 6 in Las Vegas and got smothered by Nurmagomedov, who retained his UFC lightweight champion by fourth-round submission.

Then things got crazy, as Nuremagomedov leaped over the cage to attack one of McGregor's cornermen and some of Nurmagomedov's teammates entered the cage to attack McGregor. Mayhem ensued, and both fighters had to be escorted from the arena by security.

The UFC 229 matchup featured the biggest star in the sport's history against one of its most dominant fighters. Add in the fact they had bad blood from outside the Octagon, stemming from the bus attack incident in Brooklyn back in April, and you had what many considered the biggest fight in MMA history.